Substitute characters into values with no set left bits;
check if the next position is a vowel(or whatever), turn it into a
value with no right bits set, join the two characters
into a single byte, delete the unused position now.

for(int i = 0; i < str.length(); i++)
{  
   /*swaps common letters with stuff in the 32-47 range*/  
   str[i] = Subcipher(str[i]);
 
   if(str[i] < 127)
   {
      /*attempt to bring that common swapped stuff, below 16*/
      str[i] -= 32;
 
      /*check are bounadries!*/
      if(str.length() - 1 != i)
      {
         /*if less/equal than 00001111*/
         if(str[i] < 16)
         {
            /*is it in the alphabet range?*/
            if(str[i + 1] > 96 && str[i + 1] < 118)
            {
               temp = str[i + 1];
 
               if(temp == 'a') { temp = 128;  join = true; }
               /*...replacing vowels and stuff with no right set bits...*/
               else if(temp == 'u') { temp = 240; join = true; }
 
               if(join)
               {
                             str[i] |= temp;
                             str.erase(i + 1, 1);
                             join = false;
}   }  }  }  }  }

int ich;
...
ich = (str[i]&0xFF); // absolutely portable code